Yarn handling



J. H. TRUESDAIL YARN HANDLING Nov. 2, 1943.

Filed llay2, 1942 Jo 512 H Dues dail INVENTOR Patented Nov. 2, 1943 YARNHANDLING John Howard Truesdail, Richmond, Va.., assignor to E. I. duPont de Nemours & Company, Wilmington, Del., a corporation of DelawareApplication May 2, 1942, Serial No. 441,454

6 Claims.

a freshly spun yarn on a moving conveyor such as a belt or the like. Insuch previously proposed processes, the yarn is permitted to fall on toa slowly moving belt on which it accumulates in the form of smalloverlapping ringlets. Since the yarn is collected, free from alltension, and is purified and dried on the conveyor, it will have acrinkly form; that is, the yarn instead of being straight will becomposed of small undulations due to uneven stresses during the dryingthereof. Such a process is disclosed, for example, in British Patent No.379,880. In such a process the yarn collected on the moving conveyorbelt must be removed from the belt and wound on to a usable package.Diificulty has been experienced in removing the yarn from the belt in acontinuous uniform manner. It is particularly desirable to continuouslyremove such a yarn at a constant and uniform speed. Preferably, thisspeed is substantially the same as the speed of collection on theopposite end of the belt. Inasmuch as the yarn may dry with slightperiodic variations in the degree of crinkle, and since the drying ofsuch a yarn may involve slight variations in the degree of shrinking ofthe yarn, it is difficult to continuously remove the yarn at a givenpoint from the forward end of the conveyor. If the yarn is removed at aspeed which is too low, it will overrun the end of the belt, while if itis removed at a speed which is too high, it will be removed from thebelt too quickly, possibly before the drying is completed.

Particular difiiculty is experienced in removing the yarns from amovable conveyor when two or more such yarns are spun in side-by-sidearrangement on to a single belt conveyor. The fact that such yarns maypossess different abso lute. spinning speeds and m..y shrink oreloncluring processing to dizferent dry lengths, requires the take-upmeans or each yarn to be provided with its own individual drivingmechanism. The further fact that the spinning speed and s "inkage orelongation of a given yarn e time it is being wound on makes it verydifficult, if not to correlate in a satisfactory manner the take-upspeed and yarn speed by means of a geared mechanism.

It is an object of the present invention to provide a suitable methodand apparatus for controlling the speed of removal of a crinkly yarnwhich has been spun free of tension on to a movable conveyor means;

It is another object of this invention to provide a suitable method andapparatus for continuously removing a crinkly yarn from a given point onthe forward end of a movable conveyor on which the yarn is positioned.

Other objects of the invention will appear hereinafter.

The present invention will be more clearly understood by reference tothe following detailed description when taken in connection with theaccompanying illustration, in which:

Figure 1 is a perspective view showing an apparatus constructed inaccordance with the present invention for continuously removing acrinkly yarn from a point spaced a given distance from the forward endof a movable conveyor.

Figure 2 is a partial perspective view showing the manner in which theapparatus operates to enhance the speed of removal of the yarn.

Figure 3 is a partial perspective View showing the manner in which theapparatus operates to slow down the speed of removal of a yarn from theapparatus of the present invention.

The present invention is based primarily on the fact that a yarn whichis spun in the Wet state and collected free of all tension, except thatimposed by the weight of the yarn, on a slowly moving conveyor, andprocessed and dried on said conveyor will exhibit a crinkledform. If theyarn is drawn from the conveyor with the crinkle unremoved from theyarn, it will be removed at a considerably faster rate than if the yarnis first tensioned to remove the crinkle therefrom. The crinkle can beremoved from the yarn collected in the manner above described byapplication of a relatively small tension, such as will be exerted by asnubbing tension device of the washboard type wherein the yarn is led ina sinuous path about fixed rods.

This invention uses this tension requirement as a means of obtaining auniform take-up speed so as to maintain a constant point of yarn takeolffrom the belt. According to the principles of this invention, a suitabletensioni'ng device is so mounted along the forward end of the conveyorbelt that it will remove a portion, but only a portion, of the crinklefrom the yarn when the yarn is being removed from the belt at thedesired point spaced a given distance from the forward end of the belt.When the yarn is being removed from the belt at a point in advance ofsaid desired point, the tension device will exert less tension onthe-yarn and remove less of the crinkle therefrom, thus increasing thetake-off speed of the yarn and moving the point of yarn take-offbackwards along the belt. When the yarn is being removed from the beltat a point to the rear of the desired point, the tension device willexert a greater tension on the yarn and thus remove a greater amount ofcrinkle from the yarn. This straight ening of the yarn will eifectivelydecrease the speed of yarn removal and will advance the point of yarntake-off along the length of the belt.

Referring to the drawing, reference numeral ill designates a liquidcontainer from which the yarn i2 is removed by means of yarn forwardingroller i l and displacement roller ill. The yarn is forwarded fromrollers i l and it on to a slowly moving conveyor belt it. The yarncollects on the conveyor belt it without any ten sion placed on the yarnexcept that imposed by the weight of the wet yarn. The yarn l2 collectson the movable conveyor in the form of overlapping ringlets ill]. Theyarn o the conveyor belt may be processed with liquid processingsolutions and dried in the form in which it is collected on the belt.

It is desired that the yarn be continuously removed from the belt atapproximately the point A spaced from the forward end of the belt. Forthis purpose, a pair of fixed yarn tensioning rods 22 and 24 ispositioned in spaced relationship to each other above the point A of thebelt. The yarn is drawn from the belt under rod 2'2 and over rod 25,then through the thread guide 26 by means of yarn forwarding rollers 28and 3G. The yarn may then be passed from the forwarding rollers 28 and3H through a yarn guide 32 and twisted by means of a downtwistingapparatus 34, and wound on the pirn 3B. The ballooning of the yarncaused by the down twisting apparatus is sufficient to remove allcrinkle from the yarn as it passes from the forwarding rollers 28 and3|] to the pirn 36.

The yarn forwarding rollers 28 and 30 are nip rollers and they draw theyarn across the two yarn tensioning rods 22 and 24 and, depending uponthe degree of tension imparted to the yarn by the rods, at leastpartially, remove the crinkle from the yarn. This crinkle is removed dueto the snubbing tension imposed on the yarn as it passes acrosstensioning rods 22 and 24. As long as'the yarn passes from the belt at agiven point A from the forward end of the belt, only a part of thecrinkle will be removed from the yarn. The speed of the forwardingrollers 28 and 30 is so adjusted that the yarn with said given degree ofcrinkle-removal will continue to leave the belt at the point A spacedfrom the forward end of the belt.

If for some reason the yarn accumulates on the belt to a point inadvance of said given point A, that is, for example, to the point B, theyarn forwarding rollers 28 and 30 will draw the yarn from the belt withthe yarn only contacting one of the yarn tensioning rods, that is, yarntensioning rod 24. Under these circumstances, the snubbing tensionimposed on the yarn will be considerably less than when the yarncontacts both snubbing tensioning rods and a smaller degree of crinklewill be thereby removed from the yarn. Under these circumstances, thequantity of yarn per unit of time withdrawn from the belt by theforwarding rollers 28 and 30 will be considerably greater than in the,case above described where the yarn leaves the belt at point A andcontacts both yarn tensioning rods 22 and 24. The greater speed of yarnremoval will cause the yarn to be picked up faster from the belt untilthe point of removal recedes to point A on the belt, after which theyarn tension will be sufficient to eliminate a greater degree of crinklefrom the yarn and thereby automatically slow down the speed of yarnremoval from the belt.

In the event-that the yarn is removed fromthe belt faster thananticipated and the point of yarn removal from the belt falls behind thegiven point A, for example, to the point C shown in Figure 3, the yarnwill have a greater snubbing contact with snubbing tensioning rods 22and 2 5 and thereby will remove substantially all of the crinkle fromthe yarn being removed from.

the belt. Under these circumstances, the speed of removal of the yarnfrom the belt will be considerably lower than in the above two describedsituations and thereby permit the yarn to accumulate on the belt untilit reaches point A after which the tension on the yarn will besufficiently lessened to retain a slight degree of crinkle in the yarnand thereby continue to remove the yarn from the belt at point A fromthe forward end of the belt. As above stated, the yarn forwardingrollers 28 and 30 must be driven at such a speed that a slight degree oftension on the yarn whereby the yarn retains a slight degree of crinklewill determine the removal of the yarn from the belt at a substantiallyconstant point (point A) from the end of the belt.

As mentioned above, it is preferred that the upper nip roll possess asmooth hardened surface While the lower nip roll possesses a cork orother soft, resilient surface. Such an arrange ment aids importantly inpreventing abrasion of the crinkled yarn passing about the nip rolls,especially when the yarn is to be subsequently twisted. However, thisarrangement is not essential to the invention; if desired, the moreconventional nip roll arrangement, wherein the upper roll possesses asoft surface and the lower roll a hardened surface, can be employed.

The present invention is not limited to the controlling of the speed ofa yarn by the removal of a varying amount of crinkle from a yarn. In thecase of a wet yarn substantially all the crinkle is removed from theyarn at all times regardless of the point from which the yarn is removedfrom the belt. A wet yarn, however, readily responds totensionvariations to impart variations in stretch or elongation to theyarn. The present invention is therefore clearly applicable to regulatethe removal of a wet yarn from a given point on a belt conveyor. Theamountof elongation imparted to the yarn will determine the speed ofyarn removal and thereby determine the point of removal of the yarn fromthe belt. In other words, as in the case of the variable removal of thecrinkle of a yarn, the effective length of the yarn is varied to controlthe effective speed of removal of the yarn.

The present invention makes it possible to control the speed of yarnremoval from a slowly moving conveyor on which the yarn is collected. Bycontrolling the speed of yarn removal, the yarn can be continuouslyremoved from a point snubbing action on the yarn when it moves beon theconveyor spaced at a given distance from the forward end of theconveyor.

Since it is obvious that many changes and modifications can be made inthe above-described method and apparatus without departing from thenature and spirit of the invention, it is to be understood that theinvention is not to be limited except as set forth in the appendedclaims.

I claim:

1. The method of removing a crinkled yarn resting freely on a'movableconveyor which comprises drawing the yarn from the forward end of saidconveyor, tensioning said yarn to remove at least a portion of crinklefrom the yarn, and varying the degree of tension on the yarn to vary thedegree of crinkle removal and control the rate of yarn removal.

2. The method of removing a crinkled yarn resting freely on a movableconveyor which comprises drawing the yarn from the forward end of saidconveyor, tensioning said yarn to remove at least a portion of crinklefrom the yarn, decreasing said tension on the yarn to decrease theremoval of crinkle when the point of yarn removal is positioned on saidconveyor beyond a given point, and increasing said tension on the yarnto increase the removal of crinkle when the point of yarn removal ispositioned in back of said given point, the degree of tension andremoval of crinkle determining the rate of yarn removal. I

3. An apparatus for removing a yarn resting on a movable conveyor, yarnforwarding rolls adapted to draw the yarn from said conveyor, yarnsnubbing elements positioned to snub the yarn passing from said conveyorto said rolls, said snubbing elements positioned above a given point onsaid conveyor and arranged to decrease he yond said given point and toincrease the snubbing action when it moves back of said given point. r

4. An apparatus for removing a yarn resting on a movable conveyor, yarnforwarding rolls adapted to draw the yarn from said conveyor, yarnsnubbing elements positioned to snub the yarn passing from said conveyorto said rolls, said snubbing elements vertically spaced from. each otherabove a given point on said conveyor, said rolls arranged to draw theyarn over said snubbing elements to decrease the snubbing action on theyarn when it moves beyond said given point and to increase the snubbingaction when it moves back of said given point.

5. An apparatus for removing a yarn resting on a movable conveyor, yarnforwarding rolls adapted to draw the yarn from said conveyor, yarnsnubbing elements positioned to snub the yarn passing from said conveyorto. said rolls, said snubbing .elements comprising horizontal pinsvertically spaced from each other above a given point on said conveyor,said rolls arranged to draw the yarn over said pins to decrease thesnubbing action on the yarn when it moves beyond said given point and toincrease the snubbing action when it moves back of said given point.

6. The method of removing an elongatable yarn resting freely on amovable conveyor which comprises drawing the yarn from the forward endof said conveyor, tensioning said yarn so as to elongate said yarn, andvarying the degree of tension on the yarn to vary the eifective lengthof said yarn and thereby control the rate of yarn JOHN H. 'IRUESDAJL.

removal.

